2016 Maxima--When I reach speeds between 60 and 70, car rides rough. The rough ride seems to come and go as the car changes speed. Feels like a bumpy road. No vibration or pull in the steering wheel. Feel it in the body of the car. Have had the tires balanced twice. Didn't really help. At lower speeds, car rides very smoothly. Mileage about 25,000. Replaced the tires in Feb 2021 at about 22,000 miles with Cooper CS5 Ultra Touring V. Any ideas? Gene

 

id say a bad tire,balance or a bent rim
seeing as it comes and goes with speed difference then thats about all it can be.
if its felt in the steering wheel then its most likely in the front,if felt in the seats then its likely in the rear tires.

 

Once you have tried everything else you may want to try this. I, too, had a high speed vibration that was hard to fix. It was so bad the steering wheel would move back and forth about a quarter of ah inch. I had the tires balanced twice by a tire shop and finally brought it to my dealer. What they did to correct the issue was to rebalance the tires but using only stick on weighs. It worked. No more issue of vibration and steering wheel movement. Since then I always insist that only stick on weight be used when I have the wheels rebalanced, Sounds weird but it worked.